Branching catheter systems with diagnostic components for detecting and isolating fluid flow problems (e.g., leaks, occlusions, etc.) and methods for detecting and isolating fluid flow problems are disclosed. Among the fluid flow problems that may potentially be detected are leaks in the branching catheter systems (e.g., cuts, disconnected components, etc.). Another fluid flow problem that may be detected using the diagnostic systems of the present invention is the presence of occlusions or other blockages that prevent fluid flow within the catheter systems. In addition to identifying that a problem exists, the diagnostic components may preferably also be used to identify the location of the fluid flow problem as discussed herein. Connectors for use in the branching catheter systems are also disclosed. Among the diagnostic components that may be used in branching catheter systems of the present are valves to control fluid flow through the various sections of the branching catheter system, fluid flow detectors to detect flow through the one or more sections of the branching catheter system and a control system for operating the diagnostic components.